In relation to a flowmeter that measures a volume of fluid flow, such as gases, a device that detects a leak, or the like, on the basis of a volume of fluid flow achieved during use of fluid has hitherto been proposed for a safety function of effecting a cutoff in the event of occurrence of a failure, such as a leak. Another proposed device detects a flow volume and pressure achieved during use of fluid and also detects a leak, or the like, on the basis of the flow volume and pressure (see; for instance, Patent Document 1).
The related-art example device has gas flow volume detection means, a gas pressure sensor, and gas pressure variation means. When a large flow volume is detected or when a gas appliance cannot be determined, gas supply pressure is caused to fluctuate, and occurrence of changes in flow volume corresponding to pressure fluctuations is detected, to thus detect a leak, or the like.    Patent Document 1: JP-A-2003-149075